4-[(2,4-Dichlorophenyl)carbamoyl]butanoic Acid

The synthesis and spectroscopic characterization of the glutaric acid-amide derivative, 2,4-Cl2C6H3N(H)C(=O)(CH2)3C(=O)OH (1), are described. The X-ray crystal structure determination of (1) shows the backbone of the molecule to be kinked about the methylene-C–N(amide) bond as seen in the C(p)–N–C(m)–C(m) torsion angle of −157.0(2)°; m = methylene and p = phenyl. An additional twist in the molecule is noted between the amide and phenyl groups as reflected in the C(m)–N–C(p)–C(p) torsion angle of 138.2(2)°. The most prominent feature of the molecular packing is the formation of supramolecular tapes assembled through carboxylic acid-O–H…O(carbonyl) and amide-N–H…O(amide) hydrogen bonding.

Syntheses and crystal structures of two piperine derivatives

The title compounds, 5-(2H-1,3-benzodioxol-5-yl)-N-cyclohexylpenta-2,4-dienamide, C18H21NO3 (I), and 5-(2H-1,3-benzodioxol-5-yl)-1-(pyrrolidin-1-yl)penta-2,4-dien-1-one C16H17NO3 (II), are derivatives of piperine, which is known as a pungent component of pepper. Their geometrical parameters are similar to those of the three polymorphs of piperine, which indicate conjugation of electrons over the length of the molecules. The extended structure of (I) features N—H...O amide hydrogen bonds, which generate C(4) [010] chains. The crystal of (II) features aromatic π–π stacking, as for two of three known piperine polymorphs.

Crystal structure, Hirshfeld surface analysis and computational study of the 1:2 co-crystal formed between N,N′-bis(pyridin-4-ylmethyl)ethanediamide and 4-chlorobenzoic acid

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises two half molecules of oxalamide (4 LH2), as each is disposed about a centre of inversion, and two molecules of 4-chlorobenzoic acid (CBA), each in general positions. Each 4 LH2 molecule has a (+)antiperiplanar conformation with the pyridin-4-yl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angles between the respective central core and the pyridyl rings being 68.65 (3) and 86.25 (3)°, respectively, representing the major difference between the independent 4 LH2 molecules. The anti conformation of the carbonyl groups enables the formation of intramolecular amide-N—H...O(amide) hydrogen bonds, each completing an S(5) loop. The two independent CBA molecules are similar and exhibit C6/CO2 dihedral angles of 8.06 (10) and 17.24 (8)°, indicating twisted conformations. In the crystal, two independent, three-molecule aggregates are formed via carboxylic acid-O—H...N(pyridyl) hydrogen bonding. These are connected into a supramolecular tape propagating parallel to [100] through amide-N—H...O(amide) hydrogen bonding between the independent aggregates and ten-membered {...HNC2O}2 synthons. The tapes assemble into a three-dimensional architecture through pyridyl- and methylene-C—H...O(carbonyl) and CBA-C—H...O(amide) interactions. As revealed by a more detailed analysis of the molecular packing by calculating the Hirshfeld surfaces and computational chemistry, are the presence of attractive and dispersive Cl...C=O interactions which provide interaction energies approximately one-quarter of those provided by the amide-N—H...O(amide) hydrogen bonding sustaining the supramolecular tape.

The 1:2 co-crystal formed between N,N′-bis(pyridin-4-ylmethyl)ethanediamide and benzoic acid: crystal structure, Hirshfeld surface analysis and computational study

The crystal and molecular structures of the title 1:2 co-crystal, C14H14N4O2·2C7H6O2, are described. The oxalamide molecule has a (+)-antiperiplanar conformation with the 4-pyridyl residues lying to either side of the central, almost planar C2N2O2 chromophore (r.m.s. deviation = 0.0555 Å). The benzoic acid molecules have equivalent, close to planar conformations [C6/CO2 dihedral angle = 6.33 (14) and 3.43 (10)°]. The formation of hydroxy-O—H...N(pyridyl) hydrogen bonds between the benzoic acid molecules and the pyridyl residues of the diamide leads to a three-molecule aggregate. Centrosymmetrically related aggregates assemble into a six-molecule aggregate via amide-N—H...O(amide) hydrogen bonds through a 10-membered {...HNC2O}2 synthon. These are linked into a supramolecular tape via amide-N—H...O(carbonyl) hydrogen bonds and 22-membered {...HOCO...NC4NH}2 synthons. The contacts between tapes to consolidate the three-dimensional architecture are of the type methylene-C—H...O(amide) and pyridyl-C—H...O(carbonyl). These interactions are largely electrostatic in nature. Additional non-covalent contacts are identified from an analysis of the calculated Hirshfeld surfaces.

(Z)-Selective anti-Markovnikov or Markovnikov thiol–yne-click reactions of an internal alkyne by amide hydrogen bond control

Hydrogen bonding interactions like N–H⋯S, N–H⋯N and C–H⋯O helped to obtain either (Z)-selective anti-Markovnikov or Markovnikov Thiol–Yne-Click products exclusively with excellent yields from an internal alkyne under metal free conditions.

An amide hydrogen bond templated [1]rotaxane displaying a peptide motif – demonstrating an expedient route to synthetic mimics of lasso peptides

The rapid synthesis and characterization of an amide hydrogen bond templated [1]rotaxane – demonstrating a potential pathway to synthetic analogues of lasso peptides.